My Motorsports Passion

          

 

 

 

 

Brakes are so important for a safe and fast road racing car

Data acquisition forced me to make changes to the brakes simply because the single cylinder master cylinder and larger rear brake rotors than the front brake rotors would be impossible to manage effectively. My current Allison Legacy car with it's modified engine and increased power was great to drive, however, the brakes on the stock Legacy car simply could not take the abuse of road racing, especially in the hot Texas heat and the fact that the rear brake rotors are slightly larger than the front rotors with the same Outlaw 1000 brake caliper on all 4 corners.

Initially, I removed the single brake master cylinder and bias valve and installed a new pedal assembly with dual master cylinders then went and tested. With a brake pressure sensor on the front and rear brake lines connected to the PCS D200 touch screen data acquisition, I would soon learn just how far off the brake bias was.

Using the stock Outlaw 1000 brake calipers, I ended up adjusting the bias bar so that I could brake really hard and not lock up the rear brake with 590# on the front and 370 on the rear. As the brakes heated up and the front brake pads began to heat up, this ratio would be worse. The pads were glazing over as a result of being used way beyond what the were designed for. So the next step was larger calipers and pads.

First I added powered brake fans and that still was not good enough. Without changing the front brake disc (which is custom for this spindle) I focused on the caliper. I ordered a pair of 4 piston calipers, new pads and when I had the calipers on hand, had custom billet aluminum brackets manufactured so that they could be mounted the the stock spindle. This modification literally doubled the surface area of the brake pad, in turn allowing for improved cooling by dissipating the heat out over the larger pad. Unfortunately, the earliest testing of these new brakes was just last week (Dec 22) and all I can say is wow. The difference is like day and night. Now I believe we will have a greatly improved brake package for the new car.

Additional testing still indicated that the front brakes were over heating so the next step without "reinventing the wheel", I thought, was to have the stock front brake rotors drilled and slotted as evident in the picture below. In fact, I would have the rear brake rotors drilled and slotted as well which also made an improvement in overall braking.

   

The last step to improving the breaking on this car without changing the wheel size (to use a larger diameter brake rotor) was to research what I could use on the stock spindle and bolt pattern. After weeks of searching the web on may different sites, I saw a vented rotor that I thought would work so with the model and make of car they were installed on, I went to my local auto parts store with a hub in hand and looked at the rotor fit. Ah, it would fit but we would have to change the wheel studs for longer studs. Not a problem, we needed longer studs anyway to permit the stud protrude past the lug nut as required by the rules.

I returned with the information and went to additional research for brands of brake rotors that might be available off the shelf and wheel suds that would fit our front hubs and since the rear studs were also to short, I research changing them as well. Down to the shop and I removed one of the rear axles from the car and pressed the original studs out of the axle so I could record the size, diameter and knurl diameter. The same was done for the front and with that information in hand, I researched all of the parts I would need to complete the totally new brake package.

The vented rotors for the front were originally fitted to a 1989-1996 Nissan 240 SX and to my surprise, there were performance rotors available that were drilled and slotted manufactured by Powerstop. The part numbers available from Summit Racing are PWR-JBR-502XL for the left side and PWR-JBR-502XR for the right side. (UPDATE: The Powerstop rotors are JUNK. They crack between the drilled holes and outer diameter of the rotor. The wheel studs available from Summit Racing are P# MOR-46220 for the front and P# MOR-46180 for the rear.

Once I had the rotors and studs, I now had to order new front calipers to accommodate the wider, vented rotor. I chose to use Willwood again and this part number is

Weather you would like to improve your brakes while still using your stock solid brake rotors or the vented brake rotor, I can provide you the part numbers and the custom aluminum caliper brackets. If you want to upgrade to the vented rotors as I am using now, I can provide you with those custom aluminum caliper brackets as well. Just send me an email and we can work something out.

Above you will notice that I have installed a limited slip differential in place of the aluminum spool. It makes the car so much easier to drive and maneuver in the pits. Let me know if you need the information on where you can purchase this fine piece of engineering.

 

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